docs: def cast_to_str(obj):
      """Return a string representation of a Seq or SeqRecord.
  
      Args:
          obj (str, Seq, SeqRecord): Biopython Seq or SeqRecord
  
      Returns:
          str: String representation of the sequence
  
      """
  
      if isinstance(obj, str):
          return obj
      if isinstance(obj, Seq):
          return str(obj)
      if isinstance(obj, SeqRecord):
          return str(obj.seq)
      else:
          raise ValueError('Must provide a string, Seq, or SeqRecord object.')